1. Field of the Invention
The present invention relates to a surface-conductive resin suitable for a wiring board and the like, an efficient process for forming the same, and a wiring board using the same.
2. Description of the Related Art
Various processes for metallizing the surfaces of insulating resins such as polyimide have been proposed to produce wiring boards, and the like. Of these, the dry process, which uses a vacuum device, such as a vacuum deposition device or a sputtering device, was a concrete process for forming a thin metal layer having excellent homogeneity and adhesion. However, the dry process requires a vacuum device, costly equipments such as a clean room, and the like, and it was difficult to form a thin metal layer of complex shape.
Consequently, wet processes, such as non-electrolytic metal plating which do not have the aforementioned problems, have recently been actively studied. In the wet processes such as the aforesaid non-electrolytic metal plating, etching, and the like, is generally performed as a pretreatment to form a very small hole of about 1 μm to 3 μm in the resin surface. The adhesion of the metal plating layer to the resin surface is increased by an anchor effect of the hole. However, it is inefficient to perform a pretreatment such as etching, and if it is carried out on a resin such as polyimide, in respect of that it degrades the properties of the resin, makes an anchor effect impossible and a thin metal layer with excellent homogeneity cannot be obtained.
Due to this situation, such process is desired that it has both advantages of the vacuum process and the non-electrolytic plating, and effectively form a conductive layer on a resin surface. Namely, it is desired to obtain a conductive layer having excellent electrical properties and surface flatness as obtained by the vacuum process, and simple and cost efficient manufacturing process as obtained by the non-electrolytic plating.